Method and apparatus for interconnecting distributed power sources

ABSTRACT

An apparatus and system for coupling power. In one embodiment, the apparatus comprises a trunk cable comprising a first conductor, a second conductor, and a third conductor; a first connector, wherein a first terminal of the first connector is conductively coupled to the first conductor; a second connector, wherein a first terminal of the second connector is conductively coupled to the second conductor; and a third connector, wherein a first terminal of the third connector is conductively coupled to the third conductor, and wherein the first, the second, and the third connectors are each adapted to couple to a different DC-AC power converter and an output of the trunk cable comprises three-phase AC power.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of co-pending U.S.non-provisional patent application Ser. No. 13/595,417 filed Aug. 27,2012, which is a continuation of U.S. Pat. No. 8,257,106, issued Sep. 4,2012, which claims the benefit of U.S. provisional patent applicationSer. No. 61/298,074, filed Jan. 25, 2010. Each of the aforementionedpatent applications and patents are herein incorporated by reference intheir entirety.

BACKGROUND OF THE INVENTION Field of the Invention

In one type of photovoltaic energy system, a plurality of photovoltaic(PV) modules are arranged in an array, and each module is coupled to aDC-AC inverter. The output AC energy is collected from each inverterusing a daisy chain cable that couples each inverter to each neighboringinverter. The cable is terminated in a junction box to facilitatecoupling the AC energy to the power grid. The cable interconnecting theinverters is typically custom made and assembled in the field duringinstallation of the PV module array. Such cable assembly istime-consuming, costly and fraught with error.

Therefore, there is a need in the art for an AC wiring system having astandardized format for interconnecting inverters in a photovoltaicenergy system.

SUMMARY OF THE INVENTION

Embodiments of the present invention generally relate to an apparatusand system for coupling power. In one embodiment the apparatus comprisesa trunk cable comprising a first conductor, a second conductor, and athird conductor; a first connector, wherein a first terminal of thefirst connector is conductively coupled to the first conductor; a secondconnector, wherein a first terminal of the second connector isconductively coupled to the second conductor; and a third connector,wherein a first terminal of the third connector is conductively coupledto the third conductor, and wherein the first, the second, and the thirdconnectors are each adapted to couple to a different DC-AC powerconverter and an output of the trunk cable comprises three-phase ACpower.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 depicts a block diagram of a photovoltaic energy system inaccordance with one or more embodiments of the present invention;

FIG. 2 is a block diagram of a PV module installation comprising the ACwiring system in accordance with one or more embodiments of the presentinvention;

FIG. 3 depicts a detailed perspective view of a splice box in accordancewith one or more embodiments of the present invention;

FIG. 4 depicts the splice box having the housing cover closed upon thehousing base in accordance with one or more embodiments of the presentinvention;

FIG. 5 depicts a top perspective view of the splice box and a head-onperspective view of the splice box plug in accordance with one or moreembodiments of the present invention;

FIG. 6 depicts a top perspective view and a head-on perspective view ofthe drop connector in accordance with one or more embodiments of thepresent invention;

FIG. 7 depicts a perspective view of the drop connector attached to thesplice box in accordance with one or more embodiments of the presentinvention;

FIG. 8 depicts a side and front perspective view of a splice box, a dropconnector and a drop cable in accordance with one or more embodiments ofthe present invention;

FIG. 9 depicts an exploded, perspective view of the splice box incombination with a protective plug cover and a drop connector socket incombination with a socket cover in accordance with one or moreembodiments of the present invention;

FIG. 10 depicts a termination block used to terminate the distal end ofthe trunk cable within the wiring system in accordance with one or moreembodiments of the present invention;

FIG. 11 depicts a top view of one embodiment of the junction box forcoupling the AC wiring system to the power grid in accordance with oneor more embodiments of the present invention;

FIG. 12 depicts an exploded, perspective view of a splice box and a dropconnector in accordance with one or more alternative embodiments of thepresent invention;

FIG. 13 depicts a plug cover in accordance with one or more alternativeembodiments of the present invention;

FIG. 14 depicts a socket cover in accordance with one or morealternative embodiments of the present invention;

FIG. 15 is a block diagram of a method for generating an AC wiringsystem assembly in accordance with one or more embodiments of thepresent invention;

FIG. 16 is a block diagram of an exemplary system depicting oneembodiment of phase rotation;

FIG. 17 is a block diagram of an embodiment of an exemplary string ofmicro-inverters coupled in series on a three-phase branch circuit; and

FIG. 18 is a block diagram of an embodiment of an exemplary string ofmicro-inverters coupled in series on a three-phase branch circuit.

DETAILED DESCRIPTION

FIG. 1 depicts a block diagram of a photovoltaic energy system 100 inaccordance with one or more embodiments of the present invention. Thesystem 100 comprises a plurality of photovoltaic (PV) modules 102A,102B, 102C (collectively referred to as PV modules 102), a plurality ofpower converters 104A, 104B, 104C (collectively referred to as powerconverters 104), a wiring system 106, and a junction box 114. In oneembodiment of the invention, each of the PV modules 102 is coupled to anindividual power converter 104. In other embodiments, a PV module 102may be coupled to a plurality of power converters 104, a plurality of PVmodules 102 may be coupled to a single power converter 104, or aplurality of portions of PV modules 102 may each be coupled to a powerconverter 104. In one embodiment, the power converters 104 are DC-ACinverters and the wiring system 106 carries AC power to the junction box114 and, ultimately, to the AC grid. In other embodiments, the powerconverters 104 may be DC-DC converters and the wiring system 106 maycarry DC energy to a DC-AC inverter at the junction box 114 (e.g., aplurality of DC-DC boosters coupled to a centralized DC-AC inverter viaa wiring system similar to the present disclosure). In general,embodiments of the invention interconnect a plurality of distributedpower sources (e.g., a power converter in association with a PV module).

The wiring system 106 comprises a cable 118 (trunk cable), a pluralityof splice boxes 110A-F (collectively referred to as splice boxes 110)and a termination block 108. Each of the power converters 104 arecoupled to a splice box 110 via a drop connector 112 and a drop cable116.

In the depicted embodiment, there are more splice boxes 110 than thereare power converters 104. In some embodiments, each splice box 110 iscoupled to a drop connector 112 and a drop cable 116 to an inverter. Inother embodiments, the drop connectors 112B, 112D, and 112F may be inthe form of a cap (for more details see the plug cover of FIG. 9 andFIG. 13 below) on the connector pins (plug) of the splice boxes 110B,110D, and 110F, respectively. The spacing D between splice boxes 110 isgenerally one half the distance between the centers of horizontallyaligned PV modules 102. In such an embodiment, every other splice box110 is connected to a power converter 104. Such an arrangement isdescribed with reference to FIG. 2. In an alternative embodiment wherethe PV modules 102 are vertically aligned, every splice box 110 isconnected to a power converter 104.

The wiring system 106 comprises a termination block 108 at the distalend of the cable 118. The proximal end of the cable 118 is coupled tothe junction box 114. The junction box 114 couples the proximal end ofthe cable 118 to the power grid. A detailed description of an embodimentof the termination block 108 is described with respect to FIG. 10, and adetailed description of an embodiment of the junction box is describedwith respect to FIG. 11.

The wiring system 106 can be prefabricated with the cable 118 and spliceboxes 110 prior to assembly of the photovoltaic system 100 in the field.The length of the wiring system 106 can be cut before installation ofthe system in the field or the length can be easily cut from a cablespool in the field. Once the cable 118 is cut to the length of a row ofPV modules 102, the cable 118 can be physically attached to the PVmodule 102, attached to a strut forming a support for the PV modules 102or laid inside a strut forming a support for the PV modules 102. In someembodiments, sequential numbering may be printed on the splice boxes 110(i.e., one number per box) so that, once the required number of spliceboxes 110 are determined, a user may easily identify the required lengthof the cable 118.

In one embodiment of the invention, the splice boxes 110 are attached tothe trunk cable 118 and the assembly is rolled onto a cable spool. Thesplice boxes 110 are positioned along the cable 118 at intervalsrequired for utilization with a photovoltaic module array. Aconventional PV module has the dimensions of 0.8 m width and a height1.6 m. In one embodiment, the spacing of the splice boxes 110 is 0.75 m.Using this splice box spacing enables a standard cable 118 to be usedwhen PV modules 102 are mounted in the array horizontally or vertically.When mounted horizontally (as shown in FIG. 2), every other splice box110 is coupled to a power converter 104. When mounted vertically, everysplice box 110 is coupled to a power converter 104. Thus, a single cablesystem format can be used in a PV system having any orientation of PVmodule 102. Once the PV modules 102 are mounted, the wiring system 106need only be cut to the proper length, capped at the distal end,connected to the junction box 114 at the proximal end, and the dropconnectors 112 connected to the appropriate splice boxes 110.Consequently, the speed at which a photovoltaic system can be installedis substantially enhanced.

Some embodiments of the wiring system 106 are the branch circuits 1602described below with respect to FIGS. 16-18.

FIG. 2 is a block diagram of a PV module installation 200 comprising thewiring system 106 in accordance with one or more embodiments of thepresent invention. The PV modules 102A, 102B, and 102C are horizontallyinstalled end-to-end. The splice boxes 110 are coupled to the trunkcable 118 and each spaced a distance D apart, where D is approximatelyone-half of the horizontal distance across a PV module 102. At one end,the trunk cable 118 terminates in the termination block 108; at theother end, the trunk cable 118 terminates in the junction box 114.

The splice boxes 110A, 110C, and 110E are coupled to the rear faces ofthe PV modules 102A, 102B, and 102C, respectively, proximate to thehorizontal center of each PV module 102. The splice boxes 110A, 110C,and 110E are further coupled to power converters 104A, 104B, and 104C,respectively, via drop connectors and drop cables 112A/116A, 112B/116C,and 112C/116E, respectively. The power converters 104A, 104B, and 104Care coupled to the rear face of the PV modules 102A, 102B, and 102C,respectively.

The splice boxes 110B, 110D, and 110F are unused and are terminated bythe drop connectors, or plug covers, 112B, 112D, and 112F, respectively.

FIG. 3 depicts a detailed perspective view of a splice box 110 inaccordance with one or more embodiments of the present invention. Thecable 118 is a flat cable having five fully arranged wires 312-1, 312-2,312-3, 312-4, and 312-5, collectively referred to as wires 312; in otherembodiments, the cable 118 may comprise four fully arranged wires 312.Each wire 312 comprises a wire conductor 314 surrounded by an individualinsulator, and a cable insulator circumscribes the wire insulators. Inone embodiment, the wires 312 are 12 American Wire Gauge (AWG) having acurrent rating of, for example, 20 amps and 600 V. In a four wireembodiment, the wires 312 are used for ground, neutral, and two ACphases. In a five wire embodiment, the wires 312 are used for ground,neutral, and three AC phases; alternatively, as depicted in FIG. 3, fourof the five wires 312 may be used for ground, neutral, and two AC phaseconnections, while one wire 312-5 remains unused. In other embodimentswhere the power converters 104 are DC-DC converters and the wiringsystem 106 carries DC energy, the cable 118 comprises two wires 312.

The splice box 110 shown in FIG. 3 utilizes a five wire cable 118 whereone wire 312 remains unspliced (i.e., unused). The splice box 110 isfabricated of injection-molded plastic forming a connector 302 and asplice region 306. The connector 302 comprises mechanical plug latches304 on each horizontal end of the connector 302 for mechanicallycoupling to the drop connector 112. In other embodiments, the connector302 may comprise fewer or more plug latches 304 and/or utilize othermechanisms for coupling to the drop connector 112.

Inserted into the plastic connector 302 are pins (i.e., plug pins 506described below with respect to FIG. 5) that form a plug portion of theconnector 302 (i.e., plug 303). The pins are electrically coupled tosplice box conductors 308-1, 308-2, 308-3, and 308-4 that are ultimatelycoupled to crimp connectors 310-1, 310-2, 310-3, and 310-4,respectively, within the splice region 306 of the splice box 110. Duringassembly, the wire conductors 314-1, 314-2, 314-3, and 314-4 within thecable 118 are exposed using mechanical or laser stripping to remove aportion of cable and wire insulation. In the embodiment shown in FIG. 3,the splice box 110 is installed from beneath the cable 118 and the crimpconnectors 310-1, 310-2, 310-3, and 310-4 are aligned with the exposedwire conductors 314-1, 314-2, 314-3, and 314-4, respectively. The crimpconnectors 310-1, 310-2, 310-3, and 310-4 are crimped around the exposedwire conductors 314-1, 314-2, 314-3, and 314-4, respectively, to form anelectrical contact—one pin to one wire conductor 314.

The top portion of the splice box 110 (i.e., a housing cover 338) isfolded over the bottom portion of the splice box 110 (i.e., a housingbase 336) to enclose the connections. Mechanical latches retain thehousing cover 338 to the housing base 336 to enclose the splice region.In some embodiments, such as the embodiment depicted in FIG. 3, thehousing cover 338 comprises a pair of housing latches 340 disposedperpendicular to the interior of the housing cover 338 and a pair ofhousing latches 342 disposed perpendicular to the top of the connector302. When the housing cover 338 is folded over the housing base 336, thehousing latches 340 and 342 interlock through corresponding holes in thehousing base 336 and the housing cover 338, respectively, to secure thehousing cover 338 to the housing base 336.

In an alternative embodiment, in lieu of stripping the cable 118 andwires 312 to facilitate use of crimp connectors 310, the cableinsulation may be removed and piercing connectors may be used to piercethe wire insulation to create an electrical connection to the cable wireconductors 314. In another alternative embodiment, the pierce connectorsmay be used to pierce the cable insulator and the wire insulator andmake an electrical connection to the wire conductors 314.

In one embodiment, when using three-phase power, the arrangement ofcrimp/pierce connectors to pins may be rotated by one phase in eachsplice box 110 along the cable 118. Such an implementation of phaserotation is described in detail in commonly assigned U.S. Pat. No.7,855,473, entitled “Apparatus for Phase Rotation for a Three-Phase ACCircuit”, issued Dec. 21, 2010, which is incorporated herein byreference in its entirety. Additionally, such an implementation of phaserotation is described further below within the section entitled “PhaseRotation”.

FIG. 4 depicts the splice box 110 having the housing cover 338 closedupon the housing base 336 in accordance with one or more embodiments ofthe present invention. Thereafter, an over mold (e.g., over mold 502described below with respect to FIG. 5) is applied to the splice box 110to protect the electrical connections from the environment.

FIG. 5 depicts a top perspective view of the splice box 110 and ahead-on perspective view of the splice box plug 303 in accordance withone or more embodiments of the present invention. The over mold 502 isapplied to cover the mated housing base 336/housing cover 338 such thatthe connector 302 protrudes from the over mold 502. An O-ring 504 ispositioned about the plug 303 of the splice box 110 to provide anenvironment seal when the splice box 110 is mated with the dropconnector 112.

The plug 303 comprises four plug pins 506-1, 506-2, 506-3, and 506-4,collectively referred to as plug pins 506, which are electricallycoupled to the cable wire conductors 314-1, 314-2, 314-3, and 314-4,respectively. In some other embodiments, the plug 303 comprises fivepins 506 that are electrically coupled to five cable wire conductors314. Each plug pin 506 has a pitch P with respect to the adjacent plugpin 506; in one embodiment, the plug pins 506 have a pitch of 8.5millimeters (mm). In some embodiments, one of the plug pins 506 may belonger than the remaining plug pins 506 to enable amake-first-break-last connection.

FIG. 6 depicts a top perspective view and a head-on perspective view ofthe drop connector 112 in accordance with one or more embodiments of thepresent invention. The physical shape of the drop connector 112 isdesigned to couple with the splice box connector 110 and form anenvironmentally sound connection.

The drop connector 112 comprises a socket 602 having socket latches 604disposed on each horizontal end. The socket latches 604 are of a sizeand shape to mate with the plug latches 304 of the connector 302. Thedrop connector 112 further comprises a splice hub 608 where drop cableconductors 610-1, 610-2, 610-3, and 610-4 (i.e., conductive elements,such as wire conductors, within the drop cable 116) are electricallycoupled to plug pin receptacles 612-1, 612-2, 612-3, and 612-4,respectively, of the socket 602. The plug pin receptacles 612 are of asize and shape to mate with the plug pins 506 of the connector 302,thereby electrically coupling corresponding conductors within the trunkcable 118 and the drop cable 116. In some embodiments, the dropconnector 112 comprises four plug pin receptacles 612 (e.g., forcoupling to ground, neutral, and two AC phases); alternatively, the dropconnector 112 comprises five plug pin receptacles 612 (e.g., forcoupling to ground, neutral, and three AC phases).

FIG. 7 depicts a perspective view of the drop connector 112 attached tothe splice box 110 in accordance with one or more embodiments of thepresent invention. The plug latches 304 and socket latches 604 are matedto secure the drop connector 112 to the splice box 110. In someembodiments, one of the plug latches 304 and a single correspondingsocket latch 604 may be sized differently with respect to the remainingplug latch 304/socket latch 604 to facilitate proper alignment of thedrop connector 112 with respect to the splice box 110; additionally oralternatively, one of the plug latches 304 and the corresponding socketlatch 604 may be shaped and/or oriented differently with respect to theother plug latch 304/socket latch 604 to facilitate alignment.

An extraction tool 702 is used to separate the drop connector 112 fromthe splice box 110. In some embodiments, the tool 702 is in the shape ofa two-pronged fork, where each prong suitably shaped to be insertedalong the edges of the drop connector 112 to disengage the connectorplug latches 304 from the socket latches 604 on each side of theconnector assembly. Once the tool 702 disengages the latches 304 and604, the drop connector 112 can be pulled away from the splice box 110.In other embodiments, the tool 702 may have a different shape butprovide the same functionality for disengaging the drop connector 112from the splice box 110.

FIG. 8 depicts a side and front perspective view of a splice box 110, adrop connector 112 and a drop cable 116 in accordance with one or moreembodiments of the present invention. In this embodiment, the splice box110 is shown as being attached to the PV module 102. The splice box 110,in other embodiments, may be coupled to the structural support for thePV module 102 as well as positioned within a strut of the structuralsupport. Also in this embodiment, the power converter 104 is shown asbeing attached to the PV module 102. In other embodiments, the inverter102 may be coupled to structural support for the PV module 102, to astrut of the structural support, or in another location proximate the PVmodule 102.

FIG. 9 depicts an exploded, perspective view of the splice box 110 incombination with a protective plug cover 902 (i.e., drop connectors112B, 112D, and 112E) and a drop connector socket 602 in combinationwith a socket cover 904 in accordance with one or more embodiments ofthe present invention. The plug cover 902 (or “cap”) is of a size andshape to mate with the splice box connector 302 and provide anenvironmental seal for the plug 303. The plug cover 902 is coupled tothe splice box connector 302 in the same manner that the drop connector112 is coupled to the splice box connector 302. The plug cover 902 isutilized within the wiring system 106 to protect the plug pins 506 ofany splice box 110 not being used and/or not coupled to a drop connector112. The extraction tool 702 may be used to disengage the plug latches304 from the plug cover 902 to remove the plug cover 902 from the splicebox 110.

Analogous to the plug cover 902, the socket cover 904 is of a size andshape to mate with the drop connector 112 and provide an environmentalseal for the socket 602. The socket cover 904 protects the socket plugpin receptacles 612 of a drop connector 112 when the socket 602 is notcoupled to a splice box connector 302. In some embodiments, the socketcover 904 may “snap fit” tightly to the socket 602 and not require theuse of a tool to remove the socket cover 904 from the drop connector112. Alternatively, the socket cover 904 may comprise latches analogousto the plus latches 304 for coupling to the socket latches 604; in suchembodiments, a tool such as the extraction tool 702 may be used toremove the socket cover 904 from the socket 602.

In some embodiments, the plug cover 902 and the socket cover 904 may befabricated of injection-molded plastic.

FIG. 10 depicts a termination block 108 used to terminate the distal endof the trunk cable 118 within the wiring system 106 in accordance withone or more embodiments of the present invention. The termination block108 is formed by stripping the cable insulator away from the individualwire insulators along an end portion of the cable 118. A cap 1002 havinga plurality of apertures 1004-1, 1004-2, 1004-3, 1004-4, and 1004-5(collectively referred to as apertures 1004) extending partway into thecap 1002 is attached to the end of the cable 118. The apertures 1004have a pitch equal to the pitch of the wires 312 within the cable 118.Each wire 312 is inserted into an aperture 1004. The cap 1002 is thencoupled to the cable 118 using shrink tube, wire tie, and/or other meansof attaching the cap 1002 to the cable 118 using an environmentallyprotective coupling 1006. In one embodiment, to further improve theenvironmental protection (protect the cable end from moisture ingress)the wires 312 and/or the cap 1002 may be coated with grease.

In some embodiments, the cap 1002 may have five apertures 1004; in otherembodiments, the cap 1002 may have four apertures 1004. The number ofapertures 1004 may exceed the number of wires 312 and one or moreapertures 1004 may thus remain empty when the cap 1002 is couples to thecable 118.

FIG. 11 depicts a top view of one embodiment of the junction box 114 forcoupling the wiring system 106 to the power grid in accordance with oneor more embodiments of the present invention. The junction box 114provides an environmentally protected connection between the cable wires312 of the wiring system 106 and conduit wires 1102 that connect to theAC power grid. The proximal end of the cable 118 extends throughfeedthrough 1110 in the side of the junction box 114. The insulation ofthe cable 118 is stripped to expose the cable wires 312. The insulationat the ends of the cable wires 312 is stripped to expose the wireconductors 314. Similarly, the insulation from the ends of each conduitwire 1102 is stripped to expose conduit wire conductors 1104. Theconductors 314 and 1104 exposed at the stripped ends of the wires 312and 1102, respectively, are electrically connected to one another usingtwist-on wire connectors 1106 (i.e., one twist-on wire connector foreach cable wire/conduit wire) or some other means for connecting thewire conductors to one another. In this manner, the AC power generatedby the power converters 104 and PV modules 102 is coupled to the powergrid. A cover (not shown) is placed over the junction box 114 to protectthe exposed wires from the environment.

FIG. 12 depicts an exploded, perspective view of a splice box 110 and adrop connector 112 in accordance with one or more alternativeembodiments of the present invention. The splice box 110 issubstantially rectangular in shape and comprises a housing base 1236 anda housing cover 1238 that are mated around the trunk cable 118 (i.e.,the trunk cable 118 “passes through” through splice box 110) to protectelectrical connections within the body of the splice box 110. In someembodiments, such as the embodiment depicted in FIG. 12, the trunk cable118 may be substantially round in shape rather than flat and maycomprise four or five wires, as previously described. In otherembodiments, the trunk cable 118 may be a flat cable as previouslydescribed.

The splice box 110 comprises a plug 1202 projecting from the housingcover 1238 between a pair of guide pin receptacles 1206-1 and 1206-2collectively referred to as guide pin receptacles 1206. The guide pinreceptacles 1206-1 and 1206-2 are located between a pair of releaseapertures 1208-1 and 1208-2, collectively referred to as releaseapertures 1208, although in other embodiments the release apertures 1208may be between the guide pin receptacles 1206. The plug 1202 may be partof the form factor of the housing cover 1238, and the housing cover1238, plug 1202, and housing base 1236 may be formed of injection-moldedplastic.

The plug 1202 surrounds plug pins 1204-1, 1204-2, 1204-3, and 1204-4,collectively referred to as plug pins 1204, which extend through thehousing cover 1238; in some embodiments, the plug pins 1204 may have apitch of 8.5 mm. The plug pins 1204 are formed of a conductive materialand, within the splice box 110, are coupled to wire conductors 314 ofthe cable 118 in a one-to-one correspondence. In some embodiments, thewire conductors 314 may be exposed during assembly, for example usingmechanical or laser stripping to remove a portion of cable and wireinsulation, and coupled to the plug pins 1204. Each wire conductor 314is identified as corresponding to neutral, ground, or a specific ACphase, and is electrically coupled to an individual plug pin 1204 in aone-to-one correspondence. The wire conductors 314 and plug pins 1204may be electrically coupled via soldering, crimping, or a similartechnique. In some other embodiments, the cable insulation may beremoved and piercing connectors may be used to pierce the wireinsulation to create an electrical connection between the plug pins 1204and the wire conductors 314. In certain embodiments using three-phasepower, the arrangement of crimp/pierce connectors to plug pins 1204 maybe rotated by one phase in each splice box 110 along the cable 118(i.e., a phase rotation technique may be used).

In some embodiments, each plug pin 1204 extending outward from thehousing base 1236 may be isolated from the other plug pins 1204 withinthe plug 1202 by divider walls that are part of the plug form factor.Additionally or alternatively, one of the plug pins 1204 may extendfurther outward from the housing base 1236 than the remaining plug pins1204 to enable a make-first-break-last connection.

The guide pin receptacles 1206 and release apertures 1208 arehorizontally aligned with respect to the plug 1202. The releaseapertures 1208 are generally circular in shape and extend through thewidth of the splice box 110. The guide pin receptacles 1206 are of asize and shape to mate with drop connector guide pins 1240, describedfurther below. Generally, one of the guide pin receptacles 1206, e.g.,guide pin receptacle 1206-1, may be sized differently with respect tothe remaining guide pin receptacle 1206, e.g., guide pin receptacle1206-2, to facilitate proper alignment of the drop connector 112 withrespect to the splice box 110; in some embodiments, such alignment maybe facilitated by one of the guide pin receptacles 1206 being shapedand/or oriented differently than the other guide pin receptacle 1206.

A pair of retention bars 1210-1 extend horizontally through the guidepin receptacle 1206-1 and the adjacent release aperture 1208-1, and apair of retention bars 1210-2 extend horizontally through the guide pinreceptacle 1206-2 and the adjacent release aperture 1208-2. Theretention bars 1210 retain the drop connector 112 and are positionedsuch that they may be pressed apart from one another and subsequentlyreturn to their original position; for example, the retention bars 1210may be one or more of legs of a flexible U-shaped element disposedwithin the splice box 110, held in position by spring mechanisms, or anyelement for providing the functionality described below for retainingthe drop connector or the plug cover 1302 as described further below.

The drop connector 112 comprises a socket 1248 and guide pins 1240-1 and1240-2, collectively referred to as guide pins 1240. The guide pins 1240are disposed on each horizontal side of the socket 1248. The guide pins1240-1 and 1240-2 comprise shafts 1244-1 and 1244-2, respectively, whichterminate in protuberances 1240-1 and 1240-2, respectively, and are of asize and shape to mate with the guide pin receptacles 1206-1 and 1206-2,respectively. In some embodiments, the guide pins 1240 may have across-shaped cross section.

The drop connector 112 further comprises plug pin receptacles 1246-1,1246-2, 1246-3, and 1246-4, collectively referred to as plug pinreceptacles 1246, disposed within the socket 1248. Within the dropconnector 112, each of the plug pin receptacles 1246 is electricallycoupled to a different conductive element within the drop cable 116(e.g., ground, neutral, and two AC phase wires). In some otherembodiments, the drop connector 112 may comprise five plug pinreceptacles 1246 for coupling to five wires within the drop cable 116(e.g., ground, neutral, and three AC phases). The plug pin receptacles1246 are of a size and shape to mate with the plug pins 1204 of thesplice box 110, thereby electrically coupling corresponding conductorswithin the trunk cable 118 and the drop cable 116.

When the drop connector 112 is coupled to the splice box 110, the guidepins 1240 are inserted into the guide pin receptacles 1206. Theretention bars 1210 within the guide pin receptacles 1206 are forcedapart as the protuberances 1242 pass between the retention bars 1210.The retention bars 1210 then close around the guide pin shafts 1244,locking the drop connector 112 to the splice box 110. Additionally, thesocket 1248 may snap-fit to the plug 1202 to further secure the dropconnector 112 to the splice box 110. In some embodiments, an O-ring maybe present around the plug 1202 to provide an environmental seal betweenthe drop connector 112 and the splice box 110.

In order to disengage the drop connector 112 from the splice box 110, anextraction tool 1250 may be used. In some embodiments, the extractiontool 1250 may be in the shape of a two-pronged fork with tapered prongs.To release the drop connector 112 from the splice box 110, the prongsare inserted into the release apertures 1208 to spread apart theretention bars 1210 so that the guide pin protuberances 1242 may passbetween the retention bars 1210. The drop connector 112 can then bepulled away from the splice box 110. In other embodiments, theextraction tool 702 may have a different shape but provide the samefunctionality for disengaging the drop connector 112 from the splice box110.

FIG. 13 depicts a plug cover 1302 in accordance with one or morealternative embodiments of the present invention. The plug cover 1302comprises a plug receptacle 1304 and cover guide pins 1306-1 and 1306-2.The plug cover 1302 is of a size and shape to mate with the splice box110 and provide an environmental seal for the plug 1202. The plug cover1302 is coupled to the splice box 110 in the same manner that the dropconnector 112 is coupled to the splice box 110 and is utilized toprotect the plug pins 1204 of any splice box 110 not being used and/ornot coupled to a drop connector 112. The extraction tool 1250 or asimilar tool may be used to disengage the plug cover 1302 from thesplice box 110 by inserting the extraction tool prongs into the releaseapertures 1208 and pulling the plug cover 1302 from the splice box 110.In some embodiments, the plug receptacle 1304 may “snap fit” tightly tothe plug 1202 to secure the plug cover 1302 to the splice box 110. Insome such embodiments, the cover guide pins 1306 may not be required andthe plug cover 1302 may be disengaged from the splice box 110 merely bypulling the plug cover 1302 from the splice box 110.

In some embodiments, the plug cover 1302 may be fabricated ofinjection-molded plastic.

FIG. 14 depicts a socket cover 1410 in accordance with one or morealternative embodiments of the present invention. The socket cover 1410comprises a dummy plug 1412 and guide pin receptacles 1414-2 and 1414-2.The socket cover 1410 is of a size and shape to mate with the dropconnector 112 and provide an environmental seal for the socket 602. Thesocket cover 1410 protects the socket 1248 of a drop connector 112 whennot coupled to a splice box 110. In some embodiments, the plugreceptacle 1304 may snap-fit to the socket 1248 to secure the plug coverto the drop connector 112. Additionally or alternatively, the plug cover1302 may comprise release apertures and retention bars analogous to thesplice box release apertures 1208 and retention bars 1210, respectively,for securing the socket cover 1410 to the drop connector 112. In suchembodiments, the extraction tool 1250 or a similar tool may be used todisengage the socket cover 1410 from the drop connector 112.

In some embodiments, the socket cover 1410 may be fabricated ofinjection-molded plastic.

FIG. 15 is a block diagram of a method 1500 for generating a wiringsystem assembly in accordance with one or more embodiments of thepresent invention. The wiring system assembly comprises a trunk cablecoupled to a splice box. The trunk cable is a flat trunk cable, such asthe trunk cable 118 depicted in FIG. 3, and may be coupled to a splicebox 110 as depicted in FIG. 3; alternatively, the splice box may be asdepicted in FIG. 12. The splice box comprises a plug, such as plug 303or plug 1202, for coupling the splice box to a drop connector, such asthe drop connector 112.

The method 1500 starts at step 1502 and proceeds to step 1504. At step1504, wire conductors within the flat trunk cable are exposed.Mechanical or laser stripping may be used to remove a portion of cableinsulation and wire insulation to expose the wire conductors (e.g., wireconductors 314). Each wire conductor is exposed such that it can bealigned with a splice box conductor (e.g., splice box conductors 308)which it is electrically coupled to a particular pin of the plug pin(e.g., plug pin 506). Thus, the arrangement of exposed wire conductorsto splice box conductors determines which wire of the flat cable iselectrically coupled to which pin of the splice box plug.

In some embodiments, the trunk cable may comprise four wires and allfour wire conductors are exposed for coupling to the splice boxconductors; in other embodiments, the trunk cable may comprise fivewires and four or five wire conductors are exposed.

The method 1500 proceeds to step 1504, where the exposed portion of thetrunk cable is aligned with the splice region of the splice box. Aspreviously described with respect to FIG. 3, the splice box spliceregion comprises a plurality of splice box conductors, each splice boxconductor coupled to a pin of a splice box connector in a one-to-onecorrespondence. In some embodiments, the splice box may comprise fourconductors coupled to four plug pins in a one-to-one correspondence; inother embodiments, the splice box may comprise five conductors coupledto five plug pins in a one-to-one correspondence. The trunk cable isaligned with the splice box splice region such that the exposed wireconductors are aligned with the splice box conductors corresponding tothe desired pins—i.e., each exposed wire conductor is aligned with asplice box conductor such that the wire conductor will be electricallycoupled to a particular splice box plug pin. In one embodiment usingthree-phase power, the arrangement of wire conductors to splice box plugpins may be rotated by one phase in each splice box along the cable(i.e., phase rotation may be utilized).

The method 1500 proceeds to step 1508 where the splice box conductorsare electrically coupled to the wire conductors. In some embodiments,the splice box conductors may terminate in crimp connectors (i.e., onecrimp connector per splice box conductor) for coupling to the exposedwire conductors; such a technique for coupling the cable and splice boxconductors allows a defective splice box to be easily replaced on atrunk cable. In other embodiments, other techniques for coupling thecable and splice box conductors may be used, such as soldering.

In certain embodiments, in lieu of stripping the trunk cable and wires,the trunk cable insulation may be removed and piercing connectors may beused to pierce the wire insulation to create an electrical connection tothe trunk cable wire conductors; alternatively, the pierce connectorsmay be used to pierce the cable insulator and the wire insulator andmake an electrical connection to the wire conductors. In one embodimentusing three-phase power, the arrangement of crimp/pierce connectors tosplice box plug pins may be rotated by one phase in each splice boxalong the cable (i.e., phase rotation may be utilized).

The method 1500 proceeds to step 1510 where the splice region is coveredby a housing cover. In some embodiments the housing cover may be part ofthe form factor of the splice box and can be folded over the spliceregion to mechanically couple to a splice box housing base, covering thesplice region. In other embodiments, the housing cover may be a separatepiece that is fit over the splice region and coupled to the splice boxhousing base to cover the splice region. The housing cover may besecured to the housing base by one or more mechanical latches, clips, ora similar technique.

The method 1500 proceeds to step 1512. At step 1512, an over mold, suchas the over mold 502, is applied over the mated splice box housingcover/housing base. The over mold protects the electrical connectionswithin the splice region from the environment.

The method 1500 then proceeds to step 1514 where it ends.

Phase Rotation

FIG. 16 is a block diagram of an exemplary system 1600 depicting oneembodiment of phase rotation. This diagram only portrays one variationof the myriad of possible system configurations. Phase rotation canfunction in a variety of power generation environments and systems.

The power generation system 1600 comprises a plurality of branchcircuits 1602 ₁, 1602 ₂ . . . 1602 _(m), from a load center 1608. Theload center 1608 houses connections between incoming power lines from acommercial power grid distribution system and the plurality of branchcircuits 1602 ₁, 1602 ₂ . . . 1602 _(m), collectively referred to asbranch circuits 1602. A branch circuit 1602 _(m) comprises a pluralityof micro-inverters 1606 _(1,m), 1606 _(2,m) . . . 1606 _(n,m),collectively referred to as micro-inverters 1606, coupled in series.Each micro-inverter 1606 _(1,m), 1606 _(2,m) . . . 1606 _(n,m) iscoupled to a PV module 1604 _(1,m), 1604 _(2,m) . . . 1604 _(n,m),collectively referred to as PV modules 1604.

The micro-inverters 1606 convert DC power generated by the PV modules1604 into AC power. The micro-inverters 1606 meter out current that isin-phase with the AC commercial power grid voltage and generate suchcurrent with low distortion. The system 1600 couples the generated ACpower to the commercial power grid via the load center 1608. The system1600 is one embodiment of the photovoltaic system 100 described above.

FIG. 17 is a block diagram of an embodiment of an exemplary string ofmicro-inverters 1606 coupled in series on a three-phase branch circuit1602. The branch circuit 1602 is one embodiment of the wiring system 106described above.

A load center 1730 comprises four lines L₁, L₂, L₃, and N from, forexample, a 277/480V commercial power grid supplying a commercialthree-phase AC current (herein known as “commercial AC current”). Theline L₁ carries a first phase of the commercial AC current (herein knownas “first phase of current”), the line L₂ carries a second phase of thecommercial AC current (herein known as “second phase of current”), andthe line L₃ carries a third phase of the commercial AC current (hereinknown as “third phase of current”). The line N is a neutral line thatcarries a resulting current from the sum of the first, the second, andthe third phases of current on the lines L₁, L₂, and L₃. Ideally, thefirst, the second, and the third phases of current on the lines L₁, L₂,and L₃ are equally balanced such that the magnitude of each is the sameand the phases are offset from one another by 120 degrees. When thefirst, the second, and the third phases of current on the lines L₁, L₂,and L₃ are equally balanced in this manner, the resulting current on theline N is zero.

A three-phase circuit breaker 1732 is coupled to the load center 1730 tocreate a 4-line branch circuit 1602. The branch circuit 1602 comprisesthe lines L₁, L₂, L₃, and N, a micro-inverter 1606 ₁, a micro-inverter1606 ₂, and a micro-inverter 1606 ₃, where the micro-inverters 1606 ₁,1606 ₂, and 1606 ₃ are coupled in a series configuration to the linesL₁, L₂, L₃, and N.

The micro-inverter 1606 ₁ comprises a phase rotation circuit 1702 ₁, asingle-phase DC/AC inverter 1704 ₁, input terminals 1706 ₁, 1708 ₁, 1710₁, a neutral input terminal 1718 ₁, output terminals 1712 ₁, 1714 ₁,1716 ₁, and a neutral output terminal 1720 ₁. The micro-inverter 1606 ₂and the micro-inverter 1606 ₃ are identical to the micro-inverter 1606₁. Coupling the micro-inverters 1606 ₁, 1606 ₂, and 1606 ₃ in the seriesconfiguration is as simple as coupling the output terminals 1712, 1714,1716, and the neutral output terminal 1720 of one micro-inverter 1606 tothe input terminals 1706, 1708, 1710, and the neutral input terminal1718 respectively of a next micro-inverter 1606 in the series. At theload center 1730, the lines L₁, L₂, and L₃ are coupled via thethree-phase circuit breaker 1732 to the output terminals 1712 ₃, 1714 ₃,and 1716 ₃ respectively of the micro-inverter 1606 ₃; the line N iscoupled to the neutral output terminal 1720 ₃ of the micro-inverter 1606₃. At the micro-inverter 1606 ₁, the input terminals 1706 ₁, 1708 ₁,1710 ₁, and the neutral input terminal 1718 ₁ remain uncoupled.Additionally, the micro-inverters 1606 ₁, 1606 ₂, and 1606 ₃ are eachcoupled to a PV module 1604 ₁, 1604 ₂, and 1604 ₃ respectively.

At the micro-inverter 1606 ₁, the output terminals 1712 ₁, 1714 ₁, 1716₁, and the neutral output terminal 1720 ₁ are coupled to the lines L₂,L₃, L₁, and N respectively via the micro-inverters 1606 ₂ and 1606 ₃.The DC/AC inverter 1704 ₁ injects a single phase of AC current throughthe output terminal 1712 ₁ onto the line L₂. The DC/AC inverter 1704 ₁matches the phase of the injected AC current to the second phase ofcurrent that is present on the line L₂.

Downstream of the output of the micro-inverter 1606 ₁, the lines L₂, L₃,L₁, and N are coupled to the input terminals 1706 ₂, 1708 ₂, 1710 ₂, andthe neutral input terminal 1718 ₂ respectively of the micro-inverter1606 ₂. The phase rotation circuit 1702 ₂ couples the input terminals1706 ₂, 1708 ₂, 1710 ₂, and the neutral input terminal 1718 ₂ to theoutput terminals 1716 ₂, 1712 ₂, 1714 ₂, and the neutral output terminal1720 ₂ respectively; the lines L₃, L₁, L₂, and N are therefore coupledto the output terminals 1712 ₂, 1714 ₂, 1716 ₂, and the neutral outputterminal 1720 ₂ respectively. The DC/AC inverter 1704 ₂ injects a singlephase of AC current through the output terminal 1712 ₂ onto the line L₃.The DC/AC inverter 1704 ₂ matches the phase of the injected AC currentto the third phase of current that is present on the line L₃.

Downstream of the output of the micro-inverter 1606 ₂, the lines L₃, L₁,L₂, and N are coupled to the input terminals 1706 ₃, 1708 ₃, 1710 ₃, andthe neutral input terminal 1718 ₃ respectively of the micro-inverter1606 ₃. The phase rotation circuit 1702 ₃ couples the input terminals1706 ₃, 1708 ₃, 1710 ₃, and the neutral input terminal 1718 ₃ to theoutput terminals 1716 ₃, 1712 ₃, 1714 ₃, and the neutral output terminal1720 ₃ respectively; the lines L₁, L₂, L₃, and N are therefore coupledto the output terminals 1712 ₃, 1714 ₃, 1716 ₃, and the neutral outputterminal 1720 ₃ respectively. The DC/AC inverter 1704 ₃ injects a singlephase of AC current through the output terminal 1712 ₃ onto the line L₁.The DC/AC inverter 1704 ₃ matches the phase of the injected AC currentto the first phase of current that is present on the line L₁.

As described above, each of the phase rotation circuits 1702 rotates thefirst, the second, and the third phases of current between themicro-inverters 1606 such that a different phase of AC current,phase-matched to one of the three phases of the commercial AC current,is generated by each of the micro-inverters 1606. Assuming that the PVmodules 1604 are receiving equivalent levels of solar energy and thatthe subsequent AC currents produced by the DC/AC inverters 1704 areequivalent in magnitude, the branch circuit 1602 generates an equallybalanced three-phase AC current that is phase-matched to the commercialAC current. Therefore, the commercial AC current remains equallybalanced when the generated three-phase AC current is injected onto thecommercial power grid. In addition, a branch circuit 1602 comprising astring of micro-inverters 1606 coupled in series, where the total numberof micro-inverters 1606 in the string is a multiple of three, producesthe same result in that the three-phase AC current generated by thebranch circuit 1602 is equally balanced. This automatic balancing of thethree-phase AC current generated by the branch circuit 1602 improves theefficiency of the system 1600 and greatly simplifies installations.

FIG. 18 is a block diagram of an embodiment of an exemplary string ofmicro-inverters 1606 coupled in series on a three-phase branch circuit1602. The branch circuit 1602 is one embodiment of the wiring system 106described above.

A load center 1802 comprises four lines L₁, L₂, L₃, and N from, forexample, a 120/208V commercial power grid supplying a commercialthree-phase AC current (herein known as “commercial AC current”). Theline L₁ carries a first phase of the commercial AC current (herein knownas “first phase of current”), the line L₂ carries a second phase of thecommercial AC current (herein known as “second phase of current”), andthe line L₃ carries a third phase of the commercial AC current (hereinknown as “third phase of current”). The line N is a neutral line thatcarries a resulting current from the sum of the first, the second, andthe third phases of current on the lines L₁, L₂, and L₃. Ideally, thefirst, the second, and the third phases of current on the lines L₁, L₂,and L₃ are equally balanced such that the magnitude of each is the sameand the phases are offset from one another by 120 degrees. When thefirst, the second, and the third phases of current on the lines L₁, L₂,and L₃ are equally balanced in this manner, the resulting current on theline N is zero.

A three-phase circuit breaker 1732 is coupled to the load center 1802 tocreate a 4-line branch circuit 1602. The branch circuit 1602 comprisesthe lines L₁, L₂, L₃, and N, a micro-inverter 1606 ₁, a micro-inverter1606 ₂, and a micro-inverter 1606 ₃, where the micro-inverters 1606 ₁,1606 ₂, and 1606 ₃ are coupled in a series configuration to the linesL₁, L₂, L₃, and N.

The micro-inverter 1606 ₁ comprises a phase rotation circuit 1702 ₁, atwo-phase DC/AC inverter 1804 ₁, input terminals 1706 ₁, 1708 ₁, 1710 ₁,a neutral input terminal 1718 ₁, output terminals 1712 ₁, 1714 ₁, 1716₁, and a neutral output terminal 1720 ₁. The micro-inverter 1606 ₂ andthe micro-inverter 1606 ₃ are identical to the micro-inverter 1606 ₁.Coupling the micro-inverters 1606 ₁, 1606 ₂, and 1606 ₃ in the seriesconfiguration is as simple as coupling the output terminals 1712, 1714,1716, and the neutral output terminal 1720 of one micro-inverter 1606 tothe input terminals 1706, 1708, 1710, and the neutral input terminal1718 respectively of a next micro-inverter 1606 in the series. At theload center 1802, the lines L₁, L₂, and L₃ are coupled via thethree-phase circuit breaker 1732 to the output terminals 1712 ₃, 1714 ₃,and 1716 ₃ respectively of the micro-inverter 1606 ₃; the line N iscoupled to the neutral output terminal 1720 ₃. At the micro-inverter1606 ₁, the input terminals 1706 ₁, 1708 ₁, 1710 ₁, and the neutralinput terminal 1718 ₁ remain uncoupled. Additionally, themicro-inverters 1606 ₁, 1606 ₂, and 1606 ₃ are each coupled to a PVmodule 1604 ₁, 1604 ₂, and 1604 ₃, respectively.

At the micro-inverter 1606 ₁, the output terminals 1712 ₁, 1714 ₁, 1716₁, and the neutral output terminal 1720 ₁ are coupled to the lines L₂,L₃, L₁, and N respectively via the micro-inverters 1606 ₂ and 1606 ₃.The DC/AC inverter 1804 ₁ injects an AC current through each of theoutput terminals 1712 ₁ and 1714 ₁ onto the lines L₂ and L₃respectively. The DC/AC inverter 1804 ₁ matches the phases of theinjected AC currents to the second and the third phases of current thatare present on the lines L₂ and L₃.

Downstream of the output of the micro-inverter 1606 ₁, the lines L₂, L₃,L₁, and N are coupled to the input terminals 1706 ₂, 1708 ₂, 1710 ₂, andthe neutral input terminal 1718 ₂ respectively of the micro-inverter1606 ₂. The phase rotation circuit 1702 ₂ couples the input terminals1706 ₂, 1708 ₂, 1710 ₂, and the neutral input terminal 1718 ₂ to theoutput terminals 1716 ₂, 1712 ₂, 1714 ₂, and the neutral output terminal1720 ₂ respectively; the lines L₃, L₁, L₂, and N are therefore coupledto the output terminals 1712 ₂, 1714 ₂, 1716 ₂, and the neutral outputterminal 1720 ₂ respectively. The DC/AC inverter 1804 ₂ injects an ACcurrent through each of the output terminals 1712 ₂ and 1714 ₂ onto thelines L₃ and L₁ respectively. The DC/AC inverter 1804 ₂ matches thephases of the injected AC currents to the third and the first phases ofcurrent that are present on the lines L₃ and L₁.

Downstream of the output of the micro-inverter 1606 ₂, the lines L₃, L₁,L₂, and N are coupled to the input terminals 1706 ₃, 1708 ₃, 1710 ₃, andthe neutral input terminal 1718 ₃ respectively of the micro-inverter1606 ₃. The phase rotation circuit 1702 ₃ couples the input terminals1706 ₃, 1708 ₃, 1710 ₃, and the neutral input terminal 1718 ₃ to theoutput terminals 1716 ₃, 1712 ₃, 1714 ₃, and the neutral output terminal1720 ₃ respectively; the lines L₁, L₂, L₃, and N are therefore coupledto the output terminals 1712 ₃, 1714 ₃, 1716 ₃, and the neutral outputterminal 1720 ₃ respectively. The DC/AC inverter 1804 ₃ injects an ACcurrent through each of the output terminals 1712 ₃ and 1714 ₃ onto thelines L₁ and L2 respectively. The DC/AC inverter 1804 ₂ matches thephases of the injected AC currents to the third and the first phases ofcurrent that are present on the lines L₁ and L₂.

As described above, the phase rotation circuits 1702 rotates the first,the second, and the third phases of current between the micro-inverters1606 such that a different set of phases of AC current, where each ofthe phases is phase-matched to one of the three phases of the commercialAC current, is generated by each of the micro-inverters 1606. Assumingthat the PV modules 1604 are receiving equivalent levels of solar energyand that the subsequent AC currents produced by the DC/AC inverters 1804are equivalent in magnitude, the branch circuit 1602 generates anequally balanced three-phase AC current that is phase-matched to thecommercial AC current. Therefore, the commercial AC current remainsequally balanced when the generated three-phase AC current is injectedonto the commercial power grid. In addition, a branch circuit 1602comprising a string of micro-inverters 1606 coupled in series, where thetotal number of micro-inverters 1606 in the string is a multiple ofthree, produces the same result in that the three-phase AC currentgenerated by the branch circuit 1602 is equally balanced. This automaticbalancing of the three-phase AC current generated by the branch circuit1602 improves the efficiency of the system 1600 and greatly simplifiesinstallations.

The foregoing description of embodiments of the invention comprises anumber of elements, devices, circuits and/or assemblies that performvarious functions as described. These elements, devices, circuits,and/or assemblies are exemplary implementations of means for performingtheir respectively described functions.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

The invention claimed is:
 1. An apparatus for coupling power,comprising: a trunk cable comprising a first conductor, a secondconductor, and a third conductor; a first connector, wherein a firstterminal of the first connector is conductively coupled to the firstconductor; a second connector, wherein a first terminal of the secondconnector is conductively coupled to the second conductor; and a thirdconnector, wherein a first terminal of the third connector isconductively coupled to the third conductor, and wherein the first, thesecond, and the third connectors are each adapted to couple to adifferent DC-AC power converter and an output of the trunk cablecomprises three-phase AC power; wherein a second terminal of the firstconnector is conductively coupled to the third conductor, a secondterminal of the second connector is conductively coupled to the firstconductor, and a second terminal of the third connector is conductivelycoupled to the second conductor; and wherein connections between (a) thefirst and second terminals of each connector and (b) the first, second,and third conductors are such that phase connections at each connectorare rotated.
 2. The apparatus of claim 1, wherein a third terminal ofthe first connector is conductively coupled to the second conductor, athird terminal of the second connector is conductively coupled to thethird conductor, and a third terminal of the third connector isconductively coupled to the first conductor.
 3. The apparatus of claim1, wherein each of the different DC-AC power converters generates asingle-phase AC power.
 4. The apparatus of claim 1, wherein each of thedifferent DC-AC power converters generates two phases of AC power. 5.The apparatus of claim 1, wherein each of the different DC-AC powerconverters is coupled to a different photovoltaic (PV) module.
 6. Theapparatus of claim 1, further comprising a junction box coupled to thefirst, the second, and the third conductors.
 7. The apparatus of claim1, wherein the trunk cable further comprises a neutral line conductor,and wherein neutral terminals of each of the first connector, the secondconnector, and the third connector are conductively coupled to theneutral line conductor.
 8. A system for coupling power, comprising: aplurality of DC-AC inverters; a trunk cable comprising a firstconductor, a second conductor, and a third conductor; a first connector,wherein a first terminal of the first connector is conductively coupledto the first conductor; a second connector, wherein a first terminal ofthe second connector is conductively coupled to the second conductor;and a third connector, wherein a first terminal of the third connectoris conductively coupled to the third conductor, and wherein the first,the second, and the third connectors are each adapted to couple to adifferent DC-AC power converter of the plurality of DC-AC inverters andan output of the trunk cable comprises three-phase AC power; wherein asecond terminal of the first connector is conductively coupled to thethird conductor, a second terminal of the second connector isconductively coupled to the first conductor, and a second terminal ofthe third connector is conductively coupled to the second conductor; andwherein connections between (a) the first and second terminals of eachconnector and (b) the first, second, and third conductors are such thatphase connections at each connector are rotated.
 9. The system of claim8, wherein a third terminal of the first connector is conductivelycoupled to the second conductor, a third terminal of the secondconnector is conductively coupled to the third conductor, and a thirdterminal of the third connector is conductively coupled to the firstconductor.
 10. The system of claim 8, wherein each of the differentDC-AC power converters generates a single-phase AC power.
 11. The systemof claim 8, wherein each of the different DC-AC power convertersgenerates two phases of AC power.
 12. The system of claim 8, furthercomprising a plurality of photovoltaic (PV) modules, wherein each of thedifferent DC-AC power converters is coupled to a different PV module ofthe plurality of PV modules.
 13. The system of claim 8, furthercomprising a junction box coupled to the first, the second, and thethird conductors.
 14. The system of claim 8, wherein the trunk cablefurther comprises a neutral line conductor, and wherein neutralterminals of each of the first connector, the second connector, and thethird connector are conductively coupled to the neutral line conductor.